"I'm detailed to a fault," concedes Ivanka Trump. "When we were moving into this apartment"—a 10-room aerie high above Manhattan's Park Avenue—"and I was pregnant, I went a little nuts with the nesting instinct. For two months, I went around punch-listing every scratch on the floor, making sure each paint job was flawless. The painter practically lived with me." Then, she says with a laugh, "I had a baby and realized that everything that I'd done was going to hell very quickly. Yes, I'd gotten it perfect, but now let the slow, gradual erosion begin. Needless to say, I have mellowed."

At 30, Trump is the quintessence of the chic, modern working wife and mother, albeit with a pop-culture twist. Flanking her famous father in the Celebrity Apprentice boardroom, she offers cool, savvy observations that have catapulted the fashion-forward heiress into TV stardom—and that showcase her as the business dynamo she is off screen in her role as executive vice president of development and acquisitions for the Trump Organization. So when Trump and her husband, Jared Kushner—who runs the Observer Media Group—decided to vacate his Greenwich Village bachelor digs for their first home together, her priority was clear: proximity. "Nothing beats living two blocks from work, not to mention Central Park," she says. "At night, I can run home, give [year-old] Arabella Rose a kiss, a bottle, put her to bed, then return to the office or dinner. Anytime I have five minutes, you'll see me sprinting over to see her."

Not that she misses a beat in the business world. "Deal making has given Ivanka a great eye for nuance and detail," says Trump's decorator, Kelly Behun, who was introduced to the couple by another client, Wendi Murdoch. "During our meetings, Ivanka would be on the phone, closing a hotel deal, hit pause, say: 'Isn't that the gray you showed me two weeks ago?' push play, and keep negotiating. She doesn't anguish over decisions."

This remained true even for a project so personally significant. "Being traditional and feminine, I wanted luxury and glamour," Trump says, "while Jared gravitates toward the modern, which can be austere." Ultimately, the woman who grew up in the famous marble palaces of her parents, Donald and Ivana Trump, agreed that sleeker is better. The result is what Behun calls "modern warm": contemporary angles swathed in soothing shades, starting with the foyer and its silver-leaf wallpaper, painted with a botanical mural.

Trump's own design voice—"knowing what I like, being specific," she says—was honed spearheading design for the Trump Hotel Collection and by launching her own lines of fashion, shoes, and handbags, as well as fine jewelry in stones from diamonds to rock crystal and onyx.

As a result, adds Behun, "Ivanka had a budget. They're not extravagant." Trump says, "When I don't like something, I articulate it, but Kelly always had seven other options. The last thing I wanted was a presentation—'This is your living room.' Since I like working piecemeal, she showed me cool pieces and we designed around those." One such element is a fanciful glass light fixture by Lindsey Adelman—" the first piece I bought, and still my favorite thing"—which hangs above the dining table.

The apartment's most glorious accessory, of course, visible from every window, is the spectacular Manhattan panorama, as much fine art as the eye-popping real stuff on the walls. "We recently started collecting," says Trump. "We only buy what we absolutely love." One of the couple's prized pieces is Rob Wynne's I Walk Everyday in Search of You, which is made of oversize glass letters that line the corridor to their daughter's nursery—"my favorite room," she adds.

"As impractical as it is, what I wanted for my first baby was a simple, all-white nursery," explains Trump. "Then I started reading books that said babies need color for stimulation, and I was horrified. Within a month, I'd hung one of those ugly colored mobiles off the crib."

When she's not in her daughter's room, Trump is likely to be found in the family's gleaming, high-tech kitchen. "I didn't cook at all until I was married," admits Trump, who converted to Judaism when she wed Kushner and now keeps a kosher kitchen. "Every Friday I leave work early to make a huge meal for just the two of us. Jared walks in and I'll be on a conference call, steaming wontons, saying, 'Don't bother me now.'" She's even cured her own duck, which she wrapped in cheesecloth and duct-taped to the top of the refrigerator for three weeks. "Three years ago, I couldn't boil an egg, and now I'm curing my own duck prosciutto," she says. "I even impressed myself."

That mind-set has paid off at home. "Had I done this apartment five years ago," Trump muses, "it might not have turned out so well. But I just had fun with it. I have the good fortune to have a beautiful apartment on Park Avenue, so how much can you really mess up?" In the end, she continues, "I want a home where kids can live happily and my husband can put his feet on the table or lie on the sofa watching TV and not be worried. Nothing should be so precious that you can't use it."